Magnetron sputter source

ABSTRACT

To optimize the yield of sputtered-off material as well as the service life of the target on a magnetron source, in which simultaneously good attainable distribution values of the layer on the substrate, stable over the entire target service life, a concave sputter face  20  in a configuration with small target-substrate distance d is combined with a magnet system to form the magnetron electron trap in which the outer pole  3  of the magnetron electron trap is disposed stationarily and an eccentrically disposed inner pole  4  with a second outer pole part  11  is developed rotatable about the central source axis  6.

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to a magnetron sputter source.

Magnetron sputter sources of this type have been known for many yearsand serve for coating substrates in a vacuum. Such magnetron sputtersources are distinguished in that with the aid of a magnetic field adense plasma is generated in front of the target surface to besputtered, which permits sputtering the target through ion bombardmentat high rates and attaining a layer on the substrate with high growthrate. In such magnetron sputter sources the magnetic field serves as anelectron trap which determines significantly the discharge conditions ofthe gas discharge and plasma confinement. The magnetic field of such amagnetron electron trap is developed such that in the region of the backside of a target to be sputtered closed magnetic pole loops are disposedwhich do not intersect and, in special cases, form an annularconfiguration and can also be disposed concentrically, with thesemagnetic pole loops being disposed antipolar-wise and spaced apart suchthat field lines close between the poles and herein at least partiallypenetrate the target where they determine the electron trap effect inthe region of the sputter faces. Due to the pole loops disposed onewithin the other or concentrically, in the target surface region amagnetic field is developed in the form of a tunnel, which forms aclosed loop in which the electrons are captured and guided. Based onthis characteristic structuring of the magnetron electron trap, anannular plasma discharge is also generated with inhomogeneous plasmadensity distribution which results in the target likewise being erodednonuniformly through the nonuniform ion bombardment. In such a magnetrondischarge typically an annular erosion trench is generated duringoperation whereby also problems in the layer thickness distribution onthe substrate result and have to be solved. A further disadvantage isthat through the developing trench-form erosion pattern of the targetthe utilization of the target material becomes reduced.

These problems have already been recognized according to DE OS 27 07 144corresponding to U.S. Pat. No. 5,284,564. The solution proposed is togenerate between the loop-form plasma discharge and the target arelative movement such that the plasma sweeps over the target surface.Thereby the erosion profile on the target is to be broadened orflattened and simultaneously the layer distribution on the substratedisposed in front of it to be improved. In the case of rectangularmagnetron sputter configurations the magnet system which generates theelectron trap is moved, for example according to FIG. 1, back and forthbehind the flat target. In the case of round sputter sources, the magnetsystems according to FIGS. 22 to 25 is, for example, rotated behind thetarget about the target axis. Thereby is attained that the plasma loopsweeps over the round target plate. FIGS. 22 and 25 show in additionthat the electron trap loop can be shaped differently and can therebyaffect the resulting erosion profile.

In configurations in which the substrates are disposed stationarilyopposite the magnetron target or rotate about their internal axes in aplane in front of the target, or in which already in the substrate planeover a maximally large area high homogeneity requirements of the coatingmust be met, special problems are encountered since the distribution andthe material utilization problematic must primarily be solved already atthe source side and cannot be solved by moving the substrate past suchsource. Coating installations of this type, in which disk-formsubstrates are transferred in cycles and positioned in front of amagnetron sputter source and coated there, have greatly gained insignificance. In this way today preferably semiconductor wafers areworked or coated for the production of electronic structural components,as well as storage disks for the production of magnetic storage platesand for the production of optical and optomagnetic storage plates.

For coating stationarily disposed disk-form substrates first annularsputter sources were already used before 1980. As stated, through theannular plasma loop a pronounced annular erosion trench is developed inthe target, which leads to problems with the layer distribution on thesubstrate at high precision requirements. Therefore in the case of suchsource configurations the distance between target and the substrate tobe coated must be relatively large, typically must be in the range from60 to 100 mm. In order to attain good distribution values, in additionthe target diameter must be selected to be somewhat greater than thesubstrate diameter. The relatively large target substrate distance aswell as also the relatively large oversizing of the target diameterpractically led to the fact that the utilization of the materialsputtered off was overall poor. Due to the low economy following as aconsequence and the ever increasing distribution requirements made ofthe coating, round magnetron source configurations with rotating magnetsystems were developed, which make possible further improvements in thisrespect. In order to increase the material utilization and the coatingrate it was found that the target substrate distance and the targetdiameter had to be decreased. But this is only possible if, for one, theplasma confinement takes place such that the plasma extension does notdisturb the substrate to be coated and, for another, the target removalis homogeneous over the surface and in particular also in the proximityof the target center is sputtered off.

A first improvement step could be achieved according to a configurationsuch as is depicted in FIG. 1a. The magnet system 2 is comprised of anouter annular magnet pole 3 and an inner eccentrically offset counterpole 4. The magnet system 2 is supported rotatably about a centralrotation axis 6 and is rotated in the rotational direction 7 by a drive,such as with an electromotor, with respect to the stationary target. Dueto the eccentric configuration of the inner pole 4, upon application ofa discharge voltage on the target 1 an eccentrically rotating plasmaloop is generated, which sweeps over a major portion of the target. InFIG. 1b this configuration is shown in cross section, wherein the magnetsystem 2 is rotatably supported about the source center axis 6 in therotational direction 7, a substrate s is disposed at a distance d(typically in the range from 40 to 60 mm) from the round target plate 1,with the target 1 being, for example, water-cooled via a cooling device8. The magnet system 2 is formed of permanent magnets 3, 4 and these aredisposed such that the outer pole 3 and the inner pole 4 are spacedapart and antipolar such that the generated field lines B penetratethrough the target 1 and form across the target surface the closedtunnel-form magnetic field loop, which forms an electron trap. Thereturn of the permanent magnets takes place across a yoke plate 5 ofhighly permeable material, such as iron, which is disposed on that sideof the permanent magnet poles which is further removed from target 1. Togenerate an eccentricity of the plasma loop, the inner pole 4 was offsetwith respect to the rotation axis 6. By choosing this eccentricity theerosion and distribution characteristic can be optimized in a certainrange.

A further significant improvement of the magnet system configuration ispossible through the completely eccentric formation of the magneticcircuit according to FIGS. 1c and 1 d. The width, depicted in FIG. 1cand substantially uniform, of the magnetic tunnel along the entireclosed loop permits a more constant and efficient electron trap effectand especially a clearer definition of the eccentricity of the plasmaloop, which leads to better results. In FIG. 1d a further embodiment isshown, in which the plasma loop is folded into itself again for examplein the form of a type of cardioid curve. Depending on the magnitude ofthe target and substrate dimensions, a large number of possible loopforms result, such as for example also folded plasma loops, which servefor optimization of the sputter and distribution conditions on thesubstrate. The advantage of these rotating configurations lies not leasttherein that the results can be well calculated in advance via thegeometric formation alone. Further simulation calculations are possiblefor the optimization of the design.

Magnetron sputter sources with round planar target and with rotatingmagnet systems have been marketed for many years by BalzersAktiengesellschaft in Liechtenstein, for example under the typedesignation ARQ 125, and are also described in the operatinginstructions (BB 800 463 BD) for the source in the first edition May1985.

A further option for affecting the erosion profile comprises shiftingthe outer magnet pole in the direction of the target sputter face,parallel to the source axis 6, as is shown in FIG. 2. Thereby the fieldline course B is changed, in particular flattened, such that the erosionprofile can be broadened. In such configurations with magnet poleselevated it is also possible to elevate the inner pole 4 in the centerif necessary also over the sputter face of the target 1 if the target inthe center has an opening provided for this purpose and the providedsputter characteristic permits such. In a stationary coatingconfiguration of substrate s this source formation has the disadvantagethat, on the one hand, relatively large target to substrate distancesare necessary, the utilization of the sputtered material which arriveson the substrate s is relatively low, since the zones in the outerregion, which cannot be utilized, are proportionally large and thetarget utilization is lower than in rotating systems.

A further and significantly improved formation of a magnetron sputtersource configuration for coating disk-form substrates s is depicted inFIG. 3 and described in EP 0 676 791 B1 corresponding to U.S. Pat. No.5,688,381. This source configuration also has elevated outer poles 3,wherein the pole region itself is preferably developed as a permanentmagnet and the magnetic return with respect to the central inner pole 4takes place across an iron yoke 5. In this source the target body 1 isdeveloped such that it is arched inwardly, thus is concave, and theelectron trap is defined such that the hollow volume generated by theinward arching of target 1 forms substantially the plasma dischargevolume. It becomes hereby possible to move with the substrate s veryclose to the target 1, for example 35 mm at a substrate diameter of 120mm, with the target diameter not being substantially larger than thesubstrate diameter. Hereby the discharge volume between the concavelydeveloped target 1 and the substrate is substantially delimited by thesubstrate and the sputter face. This results in the sputtered materialbeing transferred to a very large extent onto the substrate and themargin losses being low. With this source configuration therefore highcoating rates at very good economy are possible. Certain restrictionshowever occur thereby that the control of the erosion profile and of thedistribution and the attainment of reproducible conditions, inparticular over the target service life, is difficult in this respect.Attempts have therefore been made to affect with additional outer poleconfigurations 3 a, which are disposed between the inner pole 4 and theouter pole 3, the plasma discharge such that at deepened erosion profilea shift of the plasma ring takes place in order to attain a specificcompensation effect. At very high required distribution requirements andmaterial utilization degrees this method has, however, certainrestrictions.

SUMMARY OF THE INVENTION

The present invention therefore has as its object to eliminate thedisadvantages of prior art. In particular, the present invention has asits object to realize a magnetron sputter source with elevated outerpole magnet configuration, which combines the advantages of high sputterrates at high degrees of material utilization with very good achievabledistribution values on the substrate during the entire target servicelife, at stable and reproducible conditions. In addition, the magnetronsputter source has high overall economy.

Building on a magnetron sputter source of the above cited type thisobject is attained through its formation according to the claims.

According to the invention the annular outer pole does not lie in thesame plane as the inner pole and, in the margin region of the roundtarget body, is elevated with respect to the inner pole and therotatable magnet system part receives an inner pole disposedeccentrically to the source axis and receives a second outer pole partbetween inner pole and static outer pole such that with rotation thetunnel loop of the magnetic field eccentrically sweeps over the sputterface, at high rate and material utilization a good and stabledistribution results over the entire target service life which leads toa significant increase of economy. Preferred applications are obtainedaccording to the invention. Preferred further embodiments of theinventive magnetron sputter source are defined in the claims as well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 reproduce schematically prior art and FIGS. 4 to 8reproduce by example and schematically the configuration according tothe invention. In the Figures depict:

FIG. 1a in top view a rotatable round magnet system configuration withouter pole and with inner pole disposed eccentrically to the centralaxis according to prior art,

FIG. 1b in cross section and schematically the magnet systemconfiguration according to FIG. 1a with target and substrateconfiguration according to prior art,

FIG. 1c in top view a further rotatable magnet system configuration withthe magnet system disposed eccentrically to the rotation axis accordingto prior art,

FIG. 1d a further implementation of a rotatable eccentrically disposedmagnet system with magnet configuration similar to a cardioid,

FIG. 2 in cross section and schematically a magnetron configuration withan outer pole elevated with respect to the inner pole for stationarilydisposed substrate planes according to prior art,

FIG. 3 in cross section and schematically a further configuration withan outer pole elevated with respect to the inner pole and concavelydeveloped target according to prior art,

FIG. 4 schematically and in top view a magnet system configurationaccording to the invention with stationary outer pole and rotatableeccentrically disposed inner pole and outer pole part, with thestationary outer pole 3 being elevated with respect to the inner pole onthe target margin,

FIG. 5 a cross section of a configuration according to the inventionaccording to FIG. 4,

FIG. 6 a further example according to the invention shown in detail andschematically in section,

FIG. 7 an example of a measured curve of the average distribution on asubstrate over the target service life,

FIG. 8 the cross section profile of one half of a target as an exampleof the erosion which can be attained according to the invention over thetarget service life.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 5 is depicted a magnetron sputter source in cross section andschematically. The sputter target 1 is developed as an annular targetbody, which has substantially a concavely developed sputter face 20. Thesputter face 20 can per se also be developed such that it is planar, butthe concave development is significantly more advantageous since withsmall substrate distance d the discharge volume comprises essentiallythe sputter face 20 and the substrate face s and thus the loss zone inthe margin region is minimal. The round target 1 for coating storageplates s is advantageously developed such that it is annular whichpermits guiding an electrode 16 through in the center along the sourcecenter axis, which serves simultaneously as center mask for thedisk-form substrate s. The substrate s is disposed at a small distance dfrom target 1 and the diameter of target 1 is only slightly greater thanthe diameter of substrate s. The discharge volume formed thereby isdelimited by an electrode 15 encompassing this volume. Due to thisformation, the residual surfaces 15 and 16, which are also coated, areminimized relative to the usable surface of the substrate s and theso-called material transfer factor is thereby increased. The electrodes15 and 16 are conventionally with DC current operation switchedanodically and the target 1 cathodically. But, in known manner, suchelectrodes can also be operated floating or at a bias. The magnet systemcomprises an encompassing outer pole 3 elevated in the margin region oftarget 1 and an inner pole 4, eccentrically disposed to the source axis6 behind target 1, wherein between the inner pole 4 and the outer pole 3a second outer pole part 11 is disposed, which assumes a partialfunction of the outer pole 3. The second outer pole part 11 is, forexample, developed as a segment-like part which represents a type ofcutout from the annular outer pole 3 but is disposed offset androtatable. The poles directed toward target 1 are defined such that theinner pole 4 represents a counter pole to the outer pole 3 and to theouter pole part 11 such that the already described tunnel-form magneticfields B are generated across the sputter face 20, which forms anannular closed loop for the plasma confinement. The poles 3, 4 and 11are developed with advantage directly from permanent magnet material,wherein preferably permanent magnet material of the types rare earths isemployed such as cobalt, samarium and in particular of the typeneodymium. For the magnetic return in the back side region of thepermanent magnets in known manner iron yokes 5, 10 are employed. Theoutput pole 3 is according to the invention disposed stationarily alongthe target periphery encompassing the latter and parallel to the centralaxis 6 elevated with respect to the inner pole 4 and the second outerpole part 11 on the target margin. By the degree of elevation of theouter pole 3 with respect to the inner pole 4 within certain limits theerosion profile 21, which is generated through the sputter process ontarget 1, can be affected and optimized. But the outer pole 3 shouldadvantageously not be shifted beyond the target margin in the axialdirection 6. The eccentrically disposed inner pole 4 and the outer polepart 11, also disposed eccentrically, are mounted on a second returnyoke 10 rotatable about axis 6 and supported such that between the firstreturn yoke 5, which encompasses the second return joke 10, a small airgap is formed such that the inner pole magnets 4 and the magnets 11 ofthe outer pole part 11 with the second yoke 10 can rotate freely aboutaxis 6. The second yoke 10 is advantageously developed as a round plate,which can receive the magnets 4, 11 in a magnet casing 12. In spite ofstationary magnet system part 3, 5, through the rotation of the magnetsystem part 4, 10, 11 is achieved that the tunnel-form magnet field loopB, and thus the generated plasma ring discharge, can be movedeccentrically with respect to axis 6 and thereby the plasma sweeps overthe sputter face 20 in the desired manner. The generated erosion profile21 can hereby be predetermined and affected in the desired manner.

The source according to the invention corresponding to FIG. 5 isdepicted in top view to illustrate the exemplary magnet configuration inFIG. 4. On the return yoke 10, which, as a rule, comprises iron areeccentrically mounted magnets 4 which represent the inner pole, with theinner pole 4 being disposed eccentrically such that it extends withadvantage just into the proximity of the center axis 6. The second outerpole part 11, which is developed in the form of segments, also comprisespermanent magnets and is disposed on the round plate-form yoke spacedapart with respect to the inner pole 4 such that the magnetic fieldlines close across poles 11 and 4 and in the region, in which no secondouter pole part 11 is adjacent with respect to the inner pole 4, thefield lines close across the inner pole 4 and the outer pole 3. Themagnet system part mounted on the rotatable yoke plate 10 rotates inrotational direction 7 about the central source axis, with the outerpole 3 remaining stationary. The thereby developed eccentricallydisposed magnetron electron trap thus rotates about axis 6 and thus alsodoes the plasma loop.

The target-substrate distance to the lowest site of the concave target 1is advantageously smaller than 60 mm and values of less than 40 mm yieldvery good conditions with respect to material utilization anddistribution and values of less than 35 mm mean still better transferfactors at typical substrate disk diameters of 120 mm. In order to beable to ensure a stable plasma discharge, distances below 20 mm can nolonger be recommended. The target diameter should herein be up to 30%greater than the substrate diameter but preferably not greater than by25%. The source is advantageously suitable for disk-form substrates, inparticular with a diameter of 50 to 150 mm, wherein for those in therange of 70 to 150 mm the configuration is especially suitable and inwhich lie the typical dimensions for storage plates.

A practical and preferred embodiment example of the source according tothe invention is depicted in detail and schematically in cross sectionin FIG. 6. The sputter target 1 is preferably developed as an annularbody with an opening in the center. The annular body is advantageouslyconcave in the region of the sputter face 20, developed channel-form andespecially advantageously has substantially the form of a V. The outermargin of target 1 is disposed somewhat higher than the inner margin.The lowest point of the channels, or of the V-form sputter face 20, isdisposed with respect to the sputter axis 6 approximately at one halfthe target radius Rt. The target is cooled in the conventional mannerwith cooling means on the back side, for example with a cooling plate 27through which flows cooling water. On the sputter-face side periphery oftarget 1 is disposed an annular diaphragm 15, which is switched ascounter electrode to target 1. In the present example the anode 15 iselectrically connected to installation potential or to ground potential.The anode 15 comprises a receiving opening 28, into which the disk-formsubstrate s is placed. The configuration is developed such that withrespect to the lowest point of the sputter face 20 and the substrate adistance d of 20 to 60 mm is generated, preferably in the range from 20to 40 mm. This configuration overall forms the plasma volume, and itmust be ensured that the area of electrode 15 not utilizable for thecoating remains small. The opening 28 herein has for example a diameterof approximately 120 mm in order to be able to receive correspondingsubstrates s. To attain even better distribution values, substrates scan in the region of opening 28 additionally be also rotated about theiraxis 6 or even be disposed rotatable and slightly offset eccentricallywith respect to axis 6. It is also possible to position more than onesubstrate in plane 28. Further, by inclining the substrate plane withrespect to the vertical plane through the source axis 6, a furthersetting parameter can be introduced, if especially difficultdistribution requirements make such necessary. For optical storageplates which have an opening in the center, a central mask 16 isrequired, which simultaneously acts as mounting and as additional anode.The center mask 16 is guided through an opening of target 1 in thecenter and is advantageously cooled via a cooling means inlet 26. Inaddition, via this center mask 16 the discharge gas 25 can be supplied.The center mask is guided in its extension through the cooling plate 27and the rotatable magnet system part 4, 10, 11, 12 along axis 6. Thecenter mask 16 can also be operated such that it is electricallyfloating and in this case only the electrode 15, which encompasses thesubstrate S, is switched anodically.

The inner pole 4 disposed eccentrically with respect to the rotationaxis 6 and the second outer pole part comprise rare earth magnets andare mounted on the second iron yoke 10, which is developed as a roundcarrier plate, wherein the entire magnet system part is closed with acasing cover 12. This rotatable magnet system part is driven via adriving arrangement 30, for example an electromotor with gearing. Theouter and stationarily disposed yoke 5, which is magnetically coupledwith the rotatable yoke 10 is elevated along the periphery of target 1and in the end region carries outer pole magnets 3, which form the polessuch that over the sputter face 20 a tunnel-form magnetic field B with aclosed loop is generated. Through the rotation of the magnet system part4, 10, 11 the magnetic field loop is moved over the sputter face 20eccentrically about the central axis 6, whereby the desired erosioncharacteristic is generated. The outer pole 3 advantageously does notextend beyond the periphery of target 1 in the direction of thesubstrate plane s. Additional measures for protecting the magnets 3 andto prevent parasitic discharges in undesirable regions in the poleproximity are possible thereby that labyrinth-like and dark-spaceumbrella-like coverings between target periphery and outer pole 3 areprovided. This can, as shown in the depicted example, be combined withcorresponding formation of the outer anode 15. The entire source can inconventional manner be installed into a vacuum-tight casing 17, whichvia a vacuum seal 18 is flanged to a vacuum installation 31. A realizedmagnetron sputter source depicted by example has the followingdimensions:

target diameter: 150 mm

target thickness: 30 mm

target form: essentially V-form according to FIG. 8 where Th denotes thetarget thickness and Rt defines the target radius in mm and a thesputter original face 20

target material: silver, or silver alloy

target utilization: >45%

transfer factor of the target material: >45%

layer thickness distribution: approximately 5%

target substrate distance: d=30 mm

sputter gas and pressure: Ar, approximately 10⁻³ millibar

number of CDR coatings: >110,000/target

substrate diameter: 120 mm (CDR)

layer thickness on substrate: approximately 700 Å.

It was found that with the present invention primarily over the entiretarget service life with more than 110,000 coated storage plates a layerthickness precision over the useful area of the storage plate ofapproximately 5% could be maintained. This result is shown in FIG. 7.The distribution U in percent over the target service life, relative tothe number T1 of coated substrates s given in units of thousands, has ahighly uniform and constant course in the range of approximately 3.5 to5% distribution accuracy. A further advantage of the configurationcomprises that the target material is better utilized, wherewith, on theone hand, a relatively large number of coatings T1 is possible beforethe target 1 must be replaced and, on the other hand, material can besaved, which leads overall to greater economy. A highly significantaspect herein is moreover that over the service life TL of target 1 notonly the distribution proportions U remain constant but also thedischarge conditions. This is primarily attained through the uniform andspecific erosion characteristic of the source over the target servicelife, as is shown in FIG. 8 in conjunction with an example.

In FIG. 8 is depicted a cross section through one half of an annulartarget with V-form sputter original face 20 with profile curve a andwith two erosion profile curves b and c after different operating times.Profile b shows a formation after approximately ⅔ of the target servicelife and profile c approximately at the end of the target service life.It is immediately evident that the profiles are highly uniform andhardly differ in form and extend essentially symmetrically. This alsocauses the plasma conditions to remain constant and reproducible, evenover relatively steep erosion paths Th of target 1.

For storage plate applications of said type with diameters in the rangefrom 50 to 150 mm an annular target developed concavely is suitable,which means disposed annularly about axis 6 has preferably a type ofV-form profile. Herein the inclination of the inner face with respect toa planar face is to be selected of advantage in the range from 5 to 30degrees, preferably in the range from 10 to 20 degrees, with theinclination of the outer face to be selected in the range from 12 to 30degrees, preferably in the range from 15 to 25 degrees in order toattain good results. The lowest point of the concave target lies hereinapproximately in the central radius region of target 1, preferably inthe range of the 0.4- to the 0.7-fold of the target radius.

The sputter source according to the invention is per se suitable tosputter all known materials. The source is preferably applicable forsputtering metals or metal alloys. Reactive processes in which, inaddition to argon, also an additional reactive gas, such as for exampleoxygen or nitrogen, are employed, are also possible. Apart from a pureDC sputtering process, also high frequency, medium frequency or DC andAC superimposed processes are possible, but in particular also theoperation with pulsed or modulated feed. The source is in particularsuitable for sputtering metals and/or their alloys in DC, or DC-pulsedoperation. Due to the high target utilization and the good degree ofmaterial utilization, high service lives of the target are achievable,which makes the source well applicable for installations in which highcycle rates are to be achieved and thus high throughputs at higheconomy.

Aluminum and aluminum alloys are especially often applied, preferablyfor optical storage such as for example CDs and DVDs (L1-layer DVD9).The previously listed advantages also have the result that preciousmetals can be deposited especially economically. Herein silver and itsalloys are of special significance since silver with conventionalsources yields rather poor degrees of utilization. In particular withoptical storage plate applications such as CD-R and DVD, silver andsilver alloys are of great importance and the source according to theinvention represent hereto an especially economic solution. The sourceaccording to the invention is especially suitable for disk-form storageplates as well as also magnetic storage plates but in particular foroptical storage such as for example for CDs, CDRs, CD-RWs and farpreferred for DVDs.

The sputter source according to the invention permits combining verygood layer thickness distribution with simultaneously high transfer rateand target utilization degree, long target service life and highspecific deposition rate. Thereby that the target has great thickness atthose sites at which the essential sputter zones are located, hightarget utilization of more than 40%, even more than 45%, becomespossible, wherein through the special shaping of the configuration withrespect to the substrate a transfer factor of better than 45%, evenbetter than 50%, is possible. With round target configurationsespecially in the outer region of the target a large material proportionis present, which also ensures through the sputter zone applied in theouter regions a high material utilization. The combination of a concavetarget development at low target substrate distance and small targetdiameters with the feasibility of eroding large target thicknessesuniformly and yet to be able to attain over the entire service life agood and stable distribution, makes possible the production inparticular of storage plates in an especially economic manner. A furtheradvantage of the source configuration according to the inventioncomprises that only a portion of the magnet system can be rotatedleading to simpler manner of construction and, through the small outercircumference of the rotating magnet system part, denotes a significantadvantage for the simple construction of the cathode.

What is claimed is:
 1. Magnetron sputter source comprising: a roundtarget body (1), whose front side has a sputter face (20, 21), a magnetsystem (2, 3, 4, 5, 10, 11) comprising an inner pole (4) and an annularouter pole (3) annularly encompassing the inner pole (4), such that amagnetic field (B) develops over the sputter face (20, 21) in the formof a closed tunnel loop about a central source axis (6) of the magnetronsputter source, at least a portion of the magnet system (2, 3, 4, 5, 10,11) being supported rotatable about the source axis (6) andoperationally connected to driving means (30), the annular outer pole(3) being disposed in a different plane from the plane of the inner pole(4) and in a margin region around the round target body (1), the annularouter pole (3) being elevated and the rotatable magnet system portionreceiving the inner pole (4) which inner pole (4) is disposedeccentrically to the axis (6) and a second outer pole part (11) disposedbetween the annular outer pole (3) and the inner pole (4) and on therotatable magnet system portion, such that with rotation of therotatable magnet portion, the tunnel loop of the magnetic field (B)sweeps eccentrically over the sputter face (20, 21).
 2. Source asclaimed in claim 1, wherein the magnet system (2, 3, 4, 5, 10, 11)comprises permanent magnets.
 3. Source as claimed in claim 1, whereinthe magnet system (2, 3, 4, 5, 10, 11) comprises a magnetic yoke (5, 10)of highly permeable material for a return of magnetic field lines of theclosed tunnel loop of the magnetic field (B).
 4. Source as claimed inclaim 3, wherein the yoke (5, 10) is developed concentrically in twoparts and comprises a first outer stationary part (5) and a second innerrotatably supported part (10).
 5. Source as claimed in claim 4, whereinthe second inner rotatably supported part (10) of the yoke receives theinner pole (4) and the second outer pole part (11).
 6. Source as claimedin claim 1, wherein at least one of the poles (3, 4, 11) comprisespermanent-magnetic material.
 7. Source as claimed in claim 1, whereinthe closed tunnel loop of the magnet system is developed such that adirectional characteristic thereof with respect to sputtered-offparticles of the sputter face (20, 21) onto a flat substrate fortreatment using the source, is substantially maintained constant duringa sputter operation over the service life of the target body (1). 8.Source as claimed in claim 1, wherein the sputter face (20) is at leastin subregions developed concavely.
 9. Source as claimed in claim 1,wherein, in the source center along the source axis (6), a center mask(16) is provided, which penetrates the target body in the direction to aplane of a substrate to be treated by the source, and the mask is notelectrically connected to the target and forms a counter electrode tothe target (1) or is disposed such that it is floating.
 10. Source asclaimed in claim 1, wherein, the target body (1) encompasses annularlythe central source axis (6), and the sputter face (20) is developedconcavely or is channel-shaped.
 11. Source as claimed in claim 1,wherein, the outer pole (3) is disposed in the region of the peripheryof the target body (1) and the sputter face (20).
 12. Source as claimedin claim 1, wherein, a counter electrode (15) encompasses the targetbody (1) in the region of the sputter face periphery (20), wherein suchforms a receiving opening (28) for receiving a substrate(s).
 13. Sourceas claimed in claim 1, wherein, the greatest distance (d) between anoriginal surface of the sputter face (20) and a plane of a receivingopening (28) of the source for a substrate to be treated, is in therange from 20 to 60 mm.
 14. Source as claimed in claim 1, wherein, thereceiving opening (28) can receive a substrate with a diameter of 50 to150 mm.
 15. Source as claimed in claim 13, wherein, the diameter of thesputter face (20) is greater than the diameter of the receiving opening(28).
 16. Source as claimed in claim 13, wherein, the target body (1)comprises metal or a metal alloy.
 17. Source as claimed in claim 1, forthe sputter coating of storage plates.
 18. Source as claimed in claim15, wherein the diameter of the sputter face (20) is greater than thediameter of the receiving opening (28) by up to 30%.
 19. Source asclaimed in claim 1, wherein the target body (1) comprises one of silver,gold or aluminum.
 20. Source as claimed in claim 1, for the sputtercoating of storage plates selected from optical storage plates, CDs,CDRs, CD-RWs and DVDs.